<template>
  <!-- 商品分类导航 -->
    <div class="type-nav">
        <div class="container">
            <div @mouseenter="showShop" @mouseleave="leaveIndex">
                <h2 class="all">全部商品分类</h2>
                <transition name="sort">
                    <div class="sort" v-show="show">
                        <div class="all-sort-list2" @click="toSearch">
                            <div v-for="(item1,index) in categoryList" :key="item1.categoryId" :class="{current:curIndex===index}" class="item">
                                <h3 @mouseenter="changeIndex(index)">
                                    <a :data-categoryName="item1.categoryName" :data-category1Id="item1.categoryId">{{item1.categoryName}}</a>
                                </h3>
                                <!-- 二三级分类 -->
                                <div :style="{display:curIndex===index?'block':'none'}" class="item-list clearfix">
                                    <div v-for="item2 in item1.categoryChild" :key="item2.categoryId" class="subitem">
                                        <dl class="fore">
                                            <dt>
                                                <a :data-categoryName="item2.categoryName" :data-category2Id="item2.categoryId">{{item2.categoryName}}</a>
                                            </dt>
                                            <dd>
                                                <em v-for="item3 in item2.categoryChild" :key="item3.categoryId">
                                                    <a :data-categoryName="item3.categoryName" :data-category3Id="item3.categoryId">{{item3.categoryName}}</a>
                                                </em>
                                            </dd>
                                        </dl>
                                    </div>
                                </div>
                            </div>
                        </div>
                    </div>
                </transition>
            </div>
            <nav class="nav">
                    <a href="###">服装城</a>
                    <a href="###">美妆馆</a>
                    <a href="###">尚品汇超市</a>
                    <a href="###">全球购</a>
                    <a href="###">闪购</a>
                    <a href="###">团购</a>
                    <a href="###">有趣</a>
                    <a href="###">秒杀</a>
            </nav>
        </div>
    </div>
</template>

<script>
import {throttle} from "lodash";  // 节流操作
import { mapState } from "vuex";
export default {
  name:'cascade',
  data () {
      return {
        // 存储用户鼠标移到哪一个一级分类上面
        curIndex: -1,
        show: true  // 控制商品分类是否显示
      }
  },
  // 组件挂在完毕向服务器发请求获取数据
  mounted () {
    // 组件每切换一次,都会触发挂载函数
    if (this.$route.path!=='/home') {
        this.show = false
    }
  },
  computed:{
      ...mapState({
        //   右侧需要一个函数,当使用计算属性时会立即执行
        // 注入一个参数state,即为大仓库中的数据
          categoryList:(state)=>{
              return state.home.categorylist.slice(0, 16)
          }
      })
  },
  methods: {
    // 跳转到搜索页面
    toSearch(event){
        let {categoryname,category1id,category2id,category3id} = event.target.dataset
        if (categoryname) {
            let location = {name:'search'}
            let query = {categoryName:categoryname}
            if (category1id) {
                query.category1Id = category1id
            }else if(category2id){
                query.category2Id = category2id
            }else{
                query.category3Id = category3id
            }
            location.query = query
            location.params = this.$route.params
            this.$router.push(location)
        }
    },
    // 鼠标移入一级分类修改curIndex显示商品分类
    changeIndex: throttle(function(i){
        this.curIndex = i
    },50),
    // 显示商品分类
    showShop(){
        if (this.$route.path!=='/home') {
            this.show = true
        }
    },
    // 鼠标移出恢复curIndex,隐藏商品分类
    leaveIndex(){
        this.curIndex = -1
        if (this.$route.path!=='/home') {
            this.show = false
        }
    }
  }
}
</script>

<style lang="less" scoped>
.type-nav {
    border-bottom: 2px solid #e1251b;
    .container {
        width: 1200px;
        margin: 0 auto;
        display: flex;
        position: relative;
        .all {
            width: 210px;
            height: 45px;
            background-color: #e1251b;
            line-height: 45px;
            text-align: center;
            color: #fff;
            font-size: 14px;
            font-weight: bold;
        }
        .nav {
            a {
                height: 45px;
                margin: 0 22px;
                line-height: 45px;
                font-size: 16px;
                color: #333;
            }
        }
        .sort {
            position: absolute;
            left: 0;
            top: 45px;
            width: 210px;
            height: 461px;
            position: absolute;
            background: #fafafa;
            z-index: 999;
            .all-sort-list2 {
                .item {
                    &.current{
                        background-color: skyblue;
                    }
                    h3 {
                            line-height: 30px;
                            font-size: 14px;
                            font-weight: 400;
                            overflow: hidden;
                            padding: 0 20px;
                            margin: 0;

                            a {
                                color: #333;
                            }
                    }
                    .item-list {
                            display: none;
                            position: absolute;
                            width: 734px;
                            min-height: 460px;
                            background: #f7f7f7;
                            left: 210px;
                            border: 1px solid #ddd;
                            top: 0;
                            z-index: 9999 !important;

                            .subitem {
                                float: left;
                                width: 650px;
                                padding: 0 4px 0 8px;

                                dl {
                                    border-top: 1px solid #eee;
                                    padding: 6px 0;
                                    overflow: hidden;
                                    zoom: 1;

                                    &.fore {
                                        border-top: 0;
                                    }

                                    dt {
                                        float: left;
                                        width: 54px;
                                        line-height: 22px;
                                        text-align: right;
                                        padding: 3px 6px 0 0;
                                        font-weight: 700;
                                    }

                                    dd {
                                        float: left;
                                        width: 415px;
                                        padding: 3px 0 0;
                                        overflow: hidden;

                                        em {
                                            float: left;
                                            height: 14px;
                                            line-height: 14px;
                                            padding: 0 8px;
                                            margin-top: 5px;
                                            border-left: 1px solid #ccc;
                                        }
                                    }
                                }
                            }
                    }
                    // &:hover {
                    //     .item-list {
                    //         display: block;
                    //     }
                    // }
                }
            }
        }
            // 过渡动画开始状态
            .sort-enter{
                height: 0px;
            }
            // 过渡动画结束状态
            .sort-enter-to{
                height: 461px;
            }
            // 过渡动画持续时间
            .sort-enter-active{
                transition: all .4s;
            }
            .sort-leave-active{
                transition: all .4s;
            }
    }
}
</style>